JPS5851418A - Method of producing wire and cable - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing electric wires and cables, and particularly to a method for manufacturing electric wires and cables suitable for increasing the crosslinking speed.

Demand for electric wires and cables using insulators made from compositions obtained by crosslinking ethylene-based polymers, typically polyethylene, with organic peroxides has been increasing in recent years, and electric wire and cable manufacturers are faced with large-scale efforts. Improving productivity without making capital investment has become an extremely important issue.

Generally, this type of electric wire/cable is manufactured by continuous crosslinking, that is, a process in which extrusion and crosslinking are performed consecutively. Therefore, productivity depends on extrusion speed and crosslinking speed. In particular, the crosslinking rate is a factor that determines productivity, and attempts have been made to improve the crosslinking rate by using polyfunctional monomers. However, most polyfunctional monomers have the property of causing scorch when added in large amounts, and poor dispersion when added in small amounts, and have not been able to be used in a practically sufficient manner.

The present invention has been made in view of the above, and an object thereof is to provide a method for manufacturing electric wires and cables that can increase crosslinking speed and improve productivity.

The feature of the present invention is that the ethylene polymer contains a bifunctional acrylic acid having a medium-pressure phenyl group in the molecule. : A composition to which a methacrylic acid ester monomer is added is extruded and coated onto a conductor or internal semiconducting layer, and chemically crosslinked with an organic peroxide to produce electric wires and cables.

In order to increase the crosslinking rate, the inventors investigated the relationship between the molecular structure and reactivity of a number of polyfunctional monomers, and found that monofunctional monomers represented by methoxydiethylene glycol methacrylate and methoxydielene glycol acrylate have a high crosslinking rate. It was found that the rate could hardly be increased and in some cases the crosslinking rate could be slowed down. In order to dramatically increase the crosslinking rate of trifunctional monomers such as trimethylolpropane trimethacrylate and trimethylolpropane triacrylate, they must be added in extremely small amounts, resulting in poor dispersion within the polymer. It was found that the resulting product was uneven. Against these people 2
Functional monomers have a higher crosslinking rate than monofunctional monomers and trifunctional monomers.
It was discovered that there is something that lies between the functional monomers and is very easy to handle. However, it has been found that not just any bifunctional monomer is suitable, but one containing a phenyl group in the molecule is particularly suitable for this purpose. In other words, in terms of the relationship with the amount added.

It is clear that it is easy to disperse uniformly in the polymer, and that it has a property that it does not easily cause foaming, etc. because it has a low volatilization loss for the same molecular weight.

The bifunctional monomer having a phenyl group in its molecule as used herein is typified by 2,2'-bis(4-acryloxyphenyl)propane.

Refers to acrylate or dame acrylate having the structure (n=1 to 5). The reason why the number of n is limited to 5 or less is because if the number of n becomes larger than that, compatibility with the ethylene polymer will be lost.

In addition, although it is not necessary to separately specify the amount of these monomers added, from the viewpoint of compatibility with the ethylene polymer, polymer 10
It is desirable that the amount is within 1.0 parts by weight relative to 0 parts by weight.

ti, the ethylene polymer referred to here is an ethylene-α olefin copolymer typified by polyethylene, ethylene/vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, etc., and these are used by blending them with polyethylene. Including cases where

Dicumyl peroxide is the most suitable compound, but in some cases 1,3-bis-(1-butyl
Peroxy-isopropyl>benzene, 2,5-dimethyl-2,5-di(t-butyl peroxy)hexyne-
It is also possible to use 3 etc. As the antioxidant, thiobisalkylphenol is preferable, and there is no problem in adding lubricants such as stearic acid and metal stearate, coloring agents, carbon black, etc. as necessary. .

Next, examples of the present invention and comparative examples will be described. First, we will describe the sample preparation method and the evaluation method of crosslinking rate. For 100 parts by weight of ethylene polymer, 0.25 parts by weight of 4,4'thiobis(6Δ-t-butyl-3-methylphenol) as an antioxidant and 2.5 parts by weight of dicumyl peroxide as a crosslinking agent. , adding 0.6 to 0.5 parts by weight of a test polyfunctional monomer,
The mixture was kneaded at a temperature of 120°C using a 150 mm mixing roll, and the kneaded product was extruded and coated onto a copper conductor with an outer diameter of 3M using a 40-ran I-shaft extrusion machine to an insulation thickness of 311I11. /c4 water vapor for 5 minutes and cooled under pressure. The extrusion temperature is 12
The temperature was 5°C, and the temperature was 110°C in the cylinder part. The screw rotation speed was 11 rpm. In addition, the L/D of the screw is 21
It is. The crosslinking speed was determined from the gel fraction of the miniature cable insulator made of the above. The gel fraction was determined by extracting a sample of 0.31 with hot xylene at 110°C for 20 hours.
It was determined from the ratio of the weight after vacuum drying at 80° C. for 8 hours and the initial weight. Furthermore, the occurrence of scorch during extrusion was confirmed by visually observing the surface of the insulator of the miniature cable.

Table 1 shows the formulations and their blending amounts for examining the effects of the present invention, and Table 2 shows the comparative examples, and the blending amounts are shown in parts by weight.

No. 1 Table Table 2 Table 3 shows the test results.

Table 3 As is clear from the test results of the examples in Table 3, in the case of bifunctional acrylic acid or methacrylic acid ester monomers containing phenyl groups in the molecule, extrusion sometimes does not cause scorch, and compared to The gel fraction is higher than that of the conventional product shown in Example 1△. That is,
Effectively increases the crosslinking rate. On the other hand, when trimethylolpropane triacrylate, which is a trifunctional monomer, was added as shown in Comparative Example 3, the crosslinking rate was high, but
Produces scorch during extrusion. In addition, 1 shown in Comparative Example 4
When the functional monomer methoxydiethylene glycol acrylate was added, the crosslinking rate was not increased at all.

! 1,6-hexane glycol diacrylate gold, which is a bifunctional acrylic acid monomer that does not have a phenyl group in the molecule shown in Comparative Example 2, has a higher concentration than the above-mentioned bifunctional monomer that has a phenyl group. Low crosslinking rate. As can be seen from the above results, the electric wires and cables manufactured by the method of the present invention have a phenyl group-containing bifunctional acrylic acid or methacrylic acid ester monomer added thereto, so that the crosslinking rate of the ethylene polymer can be effectively increased. productivity can be improved. Therefore, it has extremely high industrial value.

As explained above, according to the present invention, there is an effect that the crosslinking rate can be effectively increased and productivity can be improved.

Claims (1)

[Claims] Produced by extrusion coating a conductor or internal semiconducting layer with a composition obtained by adding a bifunctional acrylic acid or methacrylic acid ester monomer having a phenyl group in the molecule to an ethylene polymer, and chemically crosslinking it with an organic peroxide. A method for manufacturing electric wires and cables characterized by: